MECHANISM OF THE ACTIVATION OF PROTEINASE-INHIBITOR SYNTHESIS BY SYSTEMIN INVOLVES BETA-SHEET STRUCTURE, A SPECIFIC DNA-BINDING PROTEIN DOMAIN

We analyzed a tertiary structure of systemin, the first identified pol ypeptide plant hormone, using two-dimensional NMR spectroscopy. From t hese data and molecular dynamics calculations we concluded that the pe ptide can adopt a Z-like-beta-sheet structure, which has previously be en found in many specific DNA-binding proteins. Using DNA-cellulose af finity chromatography, we showed that systemin binds strongly to DNA. We suggest that the specific systemin-DNA interaction, particularly in a promoter region of the proteinase inhibitors, could effect gene exp ression and thus explain the biological activity of systemin. (C) 1995 Academic Press, Inc.